Agricultural Experiment Station Researcher Discovers Herbal Treatment for Antibiotic-Resistant Staph

PLEASE NOTE: This research project has not been developed into a product that is available to consumers. No treatment for staph infections has been formulated as a result of this research.

A extract from the leaves of a bush growing on Colorado’s western slope fights resistant strains of staph infections. The discovery was made by Frank Stermitz, a Colorado State University Agricultural Experiment Station researcher and chemistry professor, and Kim Lewis, a colleague at Tufts University.

A complete article outlining the research will be published tomorrow in the Proceedings for the National Academy of Sciences.

Plants in the Berberis genus contain berberine, which has a weak ability to fight infection. An extract from some of those plants, including the barberry bush (Berberis fremontii), increases berberine’s natural antibiotic effectiveness against a resistant strain of staph, Staphylococcus aureus.

Some strains of staph have become resistant to most antibiotics. That resistance makes staph infections a major issue in hospitals, where it is a common cause of infection in surgical wounds or internal medical devices. It is also a risk to those in nursing homes and long-term care facilities. The pair’s discovery will help these facilities protect patients from these infections.

"Some medicinal plants that grow in Colorado contain antibacterial compounds," said Stermitz. "We had an idea that these plants might also contain compounds that would help natural antibacterials fight infections. We found that extracts from leaves of the barberry and Oregon grape bush enhance the potency of berberine, the natural antibiotic found in Berberis plants, against staph. These extracts inhibited berberine from being released from Staphylocossus aureus cells. That inhibits the growth of staph."

Stermitz explained that drug-resistant bacteria and infections are on the rise. Some bacteria become resistant because they develop an ability to pump antibiotics out of their cells before the drugs have a chance to work. This is called a multidrug resistant pump. Stermitz and Lewis found a compound that, when combined with berberine, stops the pump. That compound, methoxyhydnocarpin, or MHC, is found in barberry leaves. By itself, MHC is not effective in fighting staph.

"Stopping the mechanism that enables staph to be resistant to antibiotics should be of real value to health care providers," said Stermitz. He also stated that the work shows how two components of a single medicinal herb can work together to fight infection.

"Ultimately, we hope to be able to apply this compound to make drugs that would disable antibiotic resistance," said Lewis, a professor of bioengineering at Tufts. "Those drugs would ideally preserve and extend the effectiveness of antibiotic treatment for infections such as staph, meningitis and pneumonia, which are commonly treated in hospitals."

The compound was isolated from an extract of barberry leaves. The leaves used for the experiment were gathered near the western slope town of Crawford. While claims of medicinal benefits from many plants have been passed along through oral tradition in Native American and Chinese cultures, this is the first time research indicates that different components in plants’ chemistry can combine to cure alimnets.

"Until now, research has focused on finding the one element that produces a curative effect," said Stermitz. "In addition to the discovery that different molecules of a plant can work together to fight illness, this discovery has a huge effect on the ability of healthy care providers to fight staph infection because it is unlike that staph will become resistant to a medicinal herb," said Stermitz.

Other researchers who worked with Stermitz and Lewis, were Jeanne Tawara, Peter Lorenz and Lauren Zenewicz, Colorado State chemistry graduate students. The research was also supported in part by the National Science Foundation.

The scientific article describing the research can be found on the National Academy of Sciences Web site at

Colorado State Agricultural Experiment Station is a research arm of Colorado State University. In addition to Stermitz and others who work on campus, scientists are located at outreach offices of Agricultural Experiment Stations around the state, where the latest plant and animal technologies are developed and used to improve agriculture production.